The present invention relates in general to an ultrasonic test probe for inspecting an object from a remote location for locating defects therein, and more particularly, to such a probe for the inspection by means of contact type ultrasonic examination of an object, such as for example the weld areas of various nozzles provided on a nuclear reactor vessel for locating defects therein, such as cracks, voids and the like, while present in an underwater radioactive environment.
Commercial nuclear reactor vessels used in the generation of electrical power are of the pressurized water or boiling water type. In either case, the reactor vessel is generally constructed of a cylindrical metallic shell having a plurality of circumferentially spaced nozzles extending through the shell wall and welded thereto. These nozzles are of various types and are often referred to as safety injection nozzles, outlet nozzles and inlet nozzles. Thus, it can be appreciated that numerous welds are required in the fabrication of the reactor vessel, such as in securing the various nozzles to the shell wall. Although the weld areas of the reactor vessel are, of course, inspected prior to the reactor vessel's initial use, government regulations mandate in-service inspection of the reactor vessel welds.
Under such regulations, it is required that the vessel weld areas be subjected to periodic volumetric examination, whereby the structural integrity of the weld is monitored. Due to the nature of such an in-service inspection, the device designed to accomplish the specific weld examinations of the numerous nozzles must be capable of successfully operating in an underwater and radioactive environment and under remote control while maintaining a high degree of control over the placement and movement of the inspection sensors. It has been known to use ultrasonic transducers as the inspection sensors for inspecting the numerous welds of the reactor vessel using the socalled space type testing. However, in some instances, it is preferred, if not required, that the ultrasonic transducers be employed in contact type testing where the transducers are manipulated into direct contact with the surface of the nozzle at a location adjacent the weld to be examined. It is therefore desired in some instances that the ultrasonic transducers be arranged on a probe which can be inserted and manipulated within the interior of these nozzles while, for example, being in an underwater environment, and having sufficient flexibility to allow direct contact between the transducers and the examination surface of the nozzles, thereby allowing for such contact type testing.
Although there has been known the use of ultrasonic transducers mounted to a probe for inspecting the nozzle welds of a reactor vessel by space type testing, there has heretofore been unknown a flexible probe adapted for use with such transducers which permits a high degree of control over the placement and movement of the transducers to permit contact type testing in an underwater radioactive environment. Accordingly, it can be appreciated that there remains an unsolved need for such a probe for use in conducting weld examinations of reactor vessel nozzles using contact type testing.